An inflator for an inflatable vehicle occupant protection device, such as an air bag, stores a source of inflation fluid. The source of inflation fluid stored in the inflator may be pressurized or non-pressurized. For example, a pressurized source of inflation fluid may comprise pressurized fluid, or a combination of pressurized fluid and ignitable material for heating the pressurized fluid. A non-pressurized source of inflation fluid may comprise a solid, ignitable gas generating material. Such gas generating material is ignited when the vehicle experiences a collision or other condition for which inflation of the air bag is desired to protect an occupant of the vehicle. As the gas generating material burns, it generates a large volume of inflation gas which is directed to flow from the inflator into the air bag to inflate the air bag.
The gas generating material is commonly stored in an elongated cylindrical inflator housing. The housing includes an inner tubular wall and an outer tubular wall.
A tubular filter is contained in the housing concentrically between the tubular walls.
The inner tubular wall defines a cylindrical combustion chamber in which the gas generating material is contained. A plurality of gas flow openings extend through the inner tubular wall. The gas flow openings direct the inflation gas to flow radially outward from the combustion chamber and through the filter toward the outer tubular wall. The filter removes particulate matter from the inflation gas, and also cools the inflation gas, as the inflation gas flows radially outward toward the outer tubular wall. A plurality of gas outlet openings extending through the outer tubular wall direct the gas to flow radially outward from the housing toward the air bag.